I. Field of the Invention
The present invention relates to a heater for a cold start fuel injector for an internal combustion engine.
II. Description of the Prior Art
Governmental regulations restrict the maximum amount of hydrocarbon emissions as well as other emissions from an internal combustion engine. The most critical factor, however, affecting hydrocarbon emissions from an internal combustion engine occurs during the "cold start" phase of the engine start up. During the cold start phase, typically two minutes after engine ignition, the catalytic converter typically used in automotive vehicles is cold and, additionally, fuel enrichment is used to insure engine ignition. As such, during a cold start of the engine, the air/fuel ratio is much richer than stoichiometric combustion, typically 10-14:1. Furthermore, up to 50% of the hydrocarbon emissions permitted by government regulations can occur during the first 20 seconds following engine ignition.
In order to reduce hydrocarbon emissions, it is desirable to start the engine in a stoichiometric or lean state with an air/fuel ratio in the range of 14.5-16.1 depending upon the engine cylinder design and fuel composition. The spark timing is also typically retarded in order to effectively transfer heat from the combustion chamber to the catalyst in order to more quickly warm up the catalyst in the catalytic converter.
In order to provide a leaner fuel mixture during the cold start phase following engine ignition, there have been a number of previously known devices associated with cold start fuel injectors to vaporize the fuel from the cold start fuel injector prior to its induction into the engine cylinder. Vaporization of the fuel from the cold start fuel injector, of course, enables a leaner air/fuel mixture to be inducted into the engine cylinders while still insuring engine ignition during a cold start condition. However, these previously known heaters have not proven wholly satisfactory in operation.